1. Field of the Invention
The present invention relates to a quality control to enhance the reliability of a concrete structure, more particularly, to a quality control system of concrete and cement products which can check the information during manufacture of the cement products used for the structure on the construction field easily and with high reliability.
2. Prior Art
As to civil engineering-related concrete structures and buildings, it is necessary to verify the information including concrete strength and the records of construction work during maintenance or in time of disaster including earthquakes. Said information was controlled by being recorded in writing with drawings, but there was the possibility of said writing being lost or said information being falsified. In recent years said information has been recorded in the database of computers other than in writing, but there is still a risk of loss or falsification of said information. Consequently, said conventional quality control systems of concrete were not necessarily reliable to the owners and the users of concrete structures.
In addition, a method of affixing an IC tag in which the information on distribution management including building materials to building materials or wall surfaces of buildings (e.g. Patent Document 1) and a method of laying an wireless IC tag in concrete before hardening (e.g. Patent Document 2 and 3) have been devised.                [Patent Document 1] Japanese Published Unexamined Patent Application No. 2004—Gazette No. 141483        [Patent Document 2] Japanese Published Unexamined Patent Application No. 2005—Gazette No. 330729        [Patent Document 3] Japanese Published Unexamined Patent Application No. 2006—Gazette No. 183257        
However, as the above-mentioned conventional IC tag was arranged in an exposed place and needed manpower in the process from recording the information to being installed to structures, there were possibilities of the information recorded in IC tags being falsified as well as the damage or the loss of IC tags and there was also a doubt of being replaced by the falsified IC tags. If the conventional IC tags were put into concrete, there was the possibility of being damaged in the sheet-like form by considerable stress applied during kneading or casting. Furthermore, as a plane-shaped antenna was installed on the surface of the conventional tabular IC tag, a sensitivity of a directivity of an antenna for wireless contact became poorer with the peak of the orthogonal direction on the surface of the IC tag as it inclined more, and it became impossible to send or receive any data in a parallel direction to the surface of the IC tag, a narrowness of the directivity of the sensitivity of antennas was a problem.